Arrangement for controlling the supply of gas to a breathing device



Oct. 30, 1 2 I. A. HELLQUIST 3,060,933

- ARRANGEMENT FOR CONTROLLING THE SUPPLY OF GAS TO A BREATHING DEVICE Filed Jan. 24, 1957 INV E N TOR Juq/v m 001/5 Away/5 1 ATTORNEY iiniteri 3,65%3313 Patented Oct. 30, 1%62 3,969,933 ARRANGEMENT FOR CGNTROLLENG Tim 5UP- PLY F GAS TO A BREATHING DEVICE Ivan Aldine Hellquist, Solientuna, Sweden, assignor to Svenska Alttieholaget Gasaccumulator, Lidingo, Sweden, a corporation of Sweden Filed den. 24, 1957, Ser. No. 6%,170 Claims. ((ll. 128-142) The present invention refers to an arrangement for controlling the supply of gas to a breathing device and which is especially suitable to be used for pressure breathing at high altitudes.

A breathing device of this type is arranged so as to supply the pilot, during normal flight, with breathing gas, preferably pure oxygen, of the same pressure as that obtaining in the cabin. The inhalation and exhalation reistances should then be held as low as possible, such as of the order of a few millimetres Hg. This presupposes that the aircraft is fitted with a pressure cabin, so that the pressure within the cabin can be maintained largely constant independently of the altitude. It is however possible, particularly in military aircraft, for the cabin to become damaged, which makes the pressure in it go down momentarily to that of the surrounding atmosphere. This is usually referred to as explosive decompression. If the altitude of flight is then of the order of 12,000 metres, this implies that the cabin pressure is reduced toabout 130 millimetres Hg. If specific measures are not taken, the pilot will in such a case very soon be exposed to an acute oxygen shortage with peril to his life. The breathing device with which the pilot is provided is therefore arranged to supply to the pilots breathing passages and lungs, when the surrounding pressure passes below a predetermined value, pure oxygen at an overpressure of the order of 100 millimetres Hg. To enable the pilot to breathe under such a pressure, it is necessary to arrange for a compensating counterpressure of some sort to act on his body. To this end, the pilot can, for instance, be dressed in a pressure suit, whereby a uniformly distributed counter-pressure over his whole body is obtained. A somewhat handier arrangement is obtained if the pilot is provided with a capstan suit, i.e. a tightly fitting suit provided with inflatable rubber tubing in the seams thereof, so that a tightening of the cloth of the suit on the body is obtained when the tubes are inflated to a certain pressure. According to tests that have been carried out, a tube pressure of the order of 750 millimetres Hg is required to make the counterpressure distributed over the body reach a value of about 100 millimetres Hg, that is, the same order of magnitude as the overpressure supplied to the pilots breathing passages and lungs.

The present invention, which refers to a breathing device of the type referred to, presupposes that the device is provided with an inlet valve controlled by a membrane regulator, a pressure being adapted to act on the membranes inner surface, which pressure is equal to the pressure obtaining in a tube leading to a breathing mask. According to the invention, a chamber is arranged outside the membrane and provided with or forming part of a valve-controlled pressure chamber. The pressure chamber in its turn can be alternatively connected with the surrounding air or be subjected to an overpressure relative thereto. In the former case, the breathing gas will be supplied to the pilot at the same pressure as that obtaining in the surrounding air, whereas in the latter case the breathing gas will be supplied at an overpressure which is proportional to the overpressure obtaining in the pressure chamber referred to.

The invention will be described in the following in connection with the annexed drawing showing a regulator together with a part of a helmet connected thereto.-

The breathing apparatus comprises the following main components shown in the drawing. Breathing gas, such as pure oxygen, is supplied through a supply conduit 1 from a reservoir not shown in the drawing. The breathing gas flows through a main conduit 2 to an inlet valve 4 controlled by a membrane regulator 3. The gas then flows on through a tube 5 to a breathing mask, a helmet or the like. in the embodiment shown in the drawing, it is assumed that a helmet 6 is used. This is further provided with an outlet valve 7. The arrangement also comprises a pressure chamber 8 having a valve 9, by means of which the pressure on the outside of the membrane of the membrane regulator 3 is controlled. The valve 9 in its turn is controlled by the pressure within a conduit =10, which is assumed to connect to a pressure suit, the inflatable tubings of a capstan suit or some similar arrangement. Finally, the arrangement comprises a manually or aneroid-actuated two-way valve 11, by means of which the conduit 10 can be either connected to the conduits 1 and 2 or to the surrounding atmosphere.

The inlet valve 4 comprises a membrane 12, the central part of which rests on a valve seat 13 connected to the conduit 2. On the outside of the membrane 12 there is arranged a chamber 14, into which the gas can flow through a nozzle 15 inserted in the membrane 12, whereby a pressure is built up within the chamber causing the valve membrane 12 to be pressed onto the seat 13 and the valve to be shut; The chamber is provided with an outlet 15, which can be closed by a disk under'the influence of a lever 18 actuated by the membrane 17 of the membrane regulator 3. When the outlet 16 opens owing to inward bending of the membrane 17 the pressure in the chamber 14 decreases and the membrane 12 is not pressed against-the. valve seat 13 any more. This makes it possible for the breathing gas to pass from the conduit 2 into a passage 19 leading to the tube 5 and from it on to the helmet 6.

Outside the membrane 17 of the membrane regulator 3 there is arranged a chamber 20, which is in connection with the pressure chamber 8, whereby there is always the same pressure in these two chambers. The pressure chamber =8 is normally in connection with the surrounding atmosphere through a passage 21. This passage, however, is provided with the valve 9, by means of which the passage Zl-can be shut off. The valve 9 is constructed with a membrane, which is pressed against an annular valve seat when the pressure on the outside of the membrane surpasses a certain value. The membrane is further provided with a nozzle .22, which makes it possible for the gas in the space 23 outside the membrane to flow into the pressure chamber 8 and increase the pressure in it. The pressure increase in this chamber is limited to a value lying between that of the pressure in the space 23 and the pressure of the surrounding atmosphere. This is obtained by means of an aperture 24 provided in the pressure chamber. The nozzle 22 and the aperture 24- may be so dimensioned relative to each other that the pressure in the pressur chamber 8 is stabilized at a value amounting to about one fifth of the pressure in the space 23. The space 23 is connected through a passage 25 direct to the conduit 10, to which the pressure suit or the corresponding members are connected. This implies that the pressure chamber 8 is in direct connection with the surrounding air through the passage 21 as long as the pressure suit is out of operation, whereas the pressure in the pressure chamber 8 is immediately raised to a higher value as soon as the pressure suit is in its active state. In this way the requirement made on breathing devices of this type is met in that the overpressure in the helmet 6 can be activated only upon actuation of the pressure suit with the corresponding build-up of a sufiicient counterpressure over the body. a

The activation of the pressure suit is done by means of the two-way valve 11. This is arranged so as to make the conduit -10 at normal air pressure be in direct connection with the surrounding atmosphere, whereas this connection is broken and the conduit 10 instead connected to the conduits 1 and 2 having the higher pressure therein either when the pressure of the surrounding atmosphere has decreased below a predetermined value or in response to manual actuation. The valve 1 1 comprises a membrane 26, which in its inoperative position on a valve seat 27 shuts off a passage 28 connected with the conduit 10 from its connection with a passage 29 connected with the conduits .1 and 2. The membrane 26 is further directly connected through a rod 30 with a valve disk 31, which is in this position held 05 from a valve seat 32, whereby in this case a passage 28 and thereby the conduit is in direct connection with the surrounding atmosphere.

On the inside of the portion of the membrane 26 lying outside the annular seat 27 there acts an overpressure equal to the pressure in the conduits 1 and 2. In order to hold the membrane 26 in spite of this fact seated on the valve seat 27, an overpressure is maintained in the following way on the outer surface of the membrane. Outside the membrane is a chamber 33, which is connected with the passage 29 through a passage 34 of small cross-section and thus with the conduits 1 and 2. The gas therefore fiows through this passage 34 until the pressure in the chamber 33 has reached the same value as that in the conduits 1 and 2, whereby the membrane 26 is pressed against the valve seat with a force corresponding to the pressure difference within the central portion of the membrane between the pressure in the chamber 33 and that of the surrounding atmosphere.

If the pressure in the chamber 33 is brought down to that of the surrounding atmosphere, there is indeed equality between the pressures on both sides of the membrane for the central portion thereof, however, for the portion of the membrane 26 lying outside the valve seat 27 the pressure acting on the inner surface of the membrane facing the passage 29 surpasses that acting on the V outer surface, whereby the membrane is unseated and a connection established between the passages 23 and 29. The outward bending of the membrane 26 is limited by the fact that the valve disk 31 is pressed against the valve seat 32, which shuts oif the connection between the passage 28 and the surrounding air. The high pressure in the conduits 1 and 2 can therefore be translated to the conduit :10 and from it to the pressure suit or similar members. In the embodiment of the invention shown in the drawing, equalization of pressure between the chamber 33 and the surrounding atmosphere can take place either in response to an aneroid or manually. To this end, the lid member 35 is threaded into the chamber. At the foot of the thread, a number of air ports 36 are provided. Obviously, these ports are shut when the lid member is completely screwed on but are opened when the lid is turned so as to loosen it to some extent from the under-' lying parts. There is further provided in the lid memher an aperture 38 closed by a valve disk 37. The valve disk is pressed by means of'a spring against the valve seat formed at the rim of the aperture. 0n the outside of the lid 35 is arranged a cover 39 comprising a metal bellows 40, one wall of which is fixed and the other wall 41 of which is axially dis'placeablet Ports 42 are provided in the cover 39 so as to make the pressure within the cover a free wall 41 to the right at the same time as the outer air pressure strives to press the wall in the opposite direction. When the outer air pressure decreases, the wall 41 will therefore move to the right and actuate the valve disk 37 through a rod 43. When the surrounding air pressure has gone down to a certain value, the bellows 40 is able to unseat the valve disk 37 against the action of the spring acting on the valve disk and the pressure in the chamber 33. In this manner, a connection is established between chamber 33 and the surrounding atmosphere, so that the ressure in the chamber 33 decreases and the membrane 25 is lifted off the valve seat 27. A pressure decrease in the chamber 33, whether it occurs through the ports 36 or through the port 38, therefore causes switching of the two-way valve 11 and thereby an activation of the pressure suit.

When the pressure suit is activated and breathing gas under overpressure is supplied to the helmet 6, the counterpressure acting on the exhalation valve 7 of the helmet must at the same time increase to enable the pressure within the helmet to be maintained. The exhalation valve 7 is constructed as a membrane valve having a membrane 44 resting on an annular valve seat 45 under the influence of a spring 46. The latter is proportioned to allow exhalation to take place against a relatively weak counterpressure. The portion of the membrane 44 outside the valve seat 45 rests on an annular disk 47, in which a number of apertures 48 are provided. The internal diameter of the ring 47 is somewhat larger than the valve seat 45, whereby an annular slot 49 is formed between the valve seat and the ring. As long as the counterpressure in the exhalation valve is caused only by the spring 46 the membrane 44 as a whole is lifted ofi from the valve seat 45 as well as from the ring 47 causing air to escape through the ports 48 as well as through the slot 4 9. Owing to the attachment of the membrane 44 comparatively far outside the annular valve seat 45, the exhalation resistance for normal breathing is very low.

When breathing with overpressure takes place, the air pressure in a chamber 50 arranged outside the membrane "44 increases, making the membrane press with a greater force against the valve seat 45 and the ring 47. At the same time, the pressure obtaining in the ports 48 of the ring 47 has decreased. It follows from this that during the exhalation only that portion of the membrane 44 is lifted, which is inside the ring 47. The exhaled air will therefore pass only through the slot 49. In this way an automatic change in the effective membrane diameter is obtained at the moment of switching between normal breathing and overpressure breathing.

For the purpose of creating overpressure in the cham ber 50, this chamber is connected through'a tube 51 with the chamber 20 placed outside the membrane 17 and thus also with the pressure chamber 8. In dependence upon the position of the valve 22, the pressure in the three chambers 8, 20 and 50 will be either the same as that of the surrounding atmosphere or a higher pressure determined by the pressure in the conduits 1 and 2 and the dimensions of the apertures 22 and 24.

It will be apparent from the above description that under conditions of normal breathing the same pressure is present in the conduit 10 as in the surrounding atmosphere and the pressure suit is therefore not activated. Furthermore, on the outside of the membrane regulator 3 as well as on that of the exhalation valve 7, the same pressure obtains as in the surrounding atmosphere. During an inhalation, the pressure in the tube 5 decreases, the membrane 17 bends inwardly and actuates the lever 18 to open the passage 16 and decrease the pressure in the chamber. This unseats the membrane 12 of the inlet valve from the valve seat 13 and breathing gas is supplied from the conduit 2 as long as the inhalation lasts. When it has ended, the pressure mounts again in the tube 5,, the membrane 17 is again bent outwardly and the passage 16 is closed. Through the nozzle 15 pressure is built w w 1 m up rapidly in the chamber 14 and causes the membrane 12 to be reseated on the valve seat 13 and the valve 4 to be shut. During the following exhalation, the exhaled air passes through the exhalation valve 7. In this manner the breathing process continues, during which time breathing gas in dependence on the demand is supplied through the inlet valve 4. Owing to the fact that under normal breathing conditions the surrounding atmosphere acts both on the membrane 17 and on the membrane 44 in the inletand outlet valves, the pressure in the helmet 6 will always follow that of the surrounding atmosphere. In the case of high-altitude flights this presupposes that the aircraft is provided with a pressure cabin, in which a certain pressure diflerence relative to the surrounding air can be maintained over a certain altitude.

Following an explosive decompression, caused, for instance, by artillery fire or some other damage, the pres sure in the cabin goes down in the course of a very short interval of the order of a fraction of a second to reach the surrounding pressure. This causes the metal bellows 40 of the aneroid to expand and actuate the valve 37, which makes the pressure in the chamber 33 go down. As a consequence, the two-way valve 11 is switched over, the conduit and the chamber 23 connected therewith are put under pressure, whereby the pressure suit or the like is activated and the valve 9 closed. The pressure in the pressure chamber 8 and the chambers 20 and 50 connected therewith then increases, whereby the membrane 17 of the membrane regulator 3 bends inwardly, causing breathing gas to be supplied to the tube '5. (Simultaneously, the counterpressure in the exhalation valve 7 increases, allowing the pressure in the helmet 6 to rise to the desired overpressure. When this has been reached, the membrane 17 has again bent outwardly and the passage 16 been closed, causing the inlet valve 4 to close. The arrangement then continues its operation, during the whole time of which an overpressure is maintained in the helmet 6 in accordance with the pressure in the pressure chamber 8. Normal conditions are reestablished finally through the switching back of the two way valve 11.

In the embodiment described herein, the overpressure in the pressure chamber 8 was fixed at a certain value determined by the relationship between the nozzle 22 and the aperture 24. A certain overpressure in the chamber 8 can also be obtained if the aperture 24 is replaced by a spring-loaded valve in which case the spring pressure will determine the pressure that is reached in the pressure chamber 8. It is also possible to replace the aperture 24 with an aneroid-controlled restriction, in which an aneroid-controlled pin closes an aperture to a greater or lesser extent in such a way that at higher altitudes a smaller outlet cross-section and therefore a higher pressure is obtained in the chamber 8.

It was assumed in the foregoing description that there is connected with the conduit 10 a pressure suit, the inflatable tubings of a capstan suit or some similar members. In case a pressure suit is used, it may however be more suitable to connect it to the tube 5, so as to cause the same pressure to be present in the helmet and in the suit. The conduit 10 should then be shut off from outward connection at the same time as connection is maintained between the passages 25 and 28.

In the embodiment of the invention shown in the drawing, the chamber 20 communicates with the pressure chamber 8 through a special passage outside of the membrane 17. It is however obvious that a separate chamber need not be arranged outside of the membrane 17 but may form a part of the pressure chamber 8. Further modifications are possible within the scope of the succeeding claims.

What is claimed is:

1. In combination with a supply source of breathable gas, a mask, a conduit connecting said mask with the supply source, an outlet valve in said mask, said outlet valve including a membrane and an annular valve seat, a support ring for said membrane disposed concentrically with said valve seat to provide a slot between the valve seat and support, said support ring having a plurality of apertures therein, valve means connecting one side of the membrane with atmosphere during normal pressure conditions and connecting said one side of the membrane with the supply source during reduced atmospheric pressure conditions -for controlling the pressure on said side of said membrane whereby a larger area of exhaust passageways through said membrane is provided during normal pressure conditions and a reduced area of passageways is provided during reduced atmospheric pressure conditions.

2. A device of the class described, comprising a source of breathable gas, a mask, a conduit for connecting the mask with the source, a first valve in said conduit, a membrane, means engaged by said membrane for controlling the opening and closing of said first valve, one side of the said membrane being in communication with the conduit between the mask and valve, a pressure chamber, a conduit connecting the other side of said membrane with said pressure chamber, a second valve controlling the pressure in said pressure chamber, said second valve connecting said pressure chamber with atmosphere during normal atmospheric conditions, a third valve and a pressure suit conduit, said third valve con necting said pressure suit conduit and said pressure chamber with the source of high pressure gas durin reduced atmospheric conditions, thereby increasing the pressure in said pressure chamber and on the other side of the membrane.

3. A device according to claim 2 and further including an outlet valve in said mask and conduit means connecting said outlet valve with said pressure chamber, said outlet valve being urged to closed position by the pressure in said conduit means.

4. A device according to claim 2 and further including an aneroid for actuating said third valve.

5. A breathing device comprising a breathing mask, a supply source of breathable gas, a conduit connected to said breathing mask and to the supply source, an inlet valve disposed in the conduit, a membrane, means engaged by said membrane for controlling the inlet valve, one side of the membrane being in communication with the con duit between the valve and the mask, valve'means controlling the pressure on the other side of the membrane, said valve means adapted to provide communication between the other side of the membrane with atmosphere and with the supply source, a pressure chamber in communication with the other side of the membrane, said last named valve means controlling the pressure in said pressure chamber, said last named valve means including a diaphragm, said diaphragm having a nozzle therein, said nozzle providing a connection between the supply source and the pressure chamber, nozzle means connecting said pressure chamber with the atmosphere, an outlet valve on said breathing mask, and conduit means connecting said outlet valve with the other side of the membrane, said outlet valve being urged to closed position by the pressure in said conduit means.

References Cited in the file of this patent UNITED STATES PATENTS 2,449,548 Burns Sept. 21, 1948 2,703,572 Seeler Mar. 8, 1955 2,834,343 Keckler et al May 13, 1958 2,867,227 Meidenbauer Jan. 6, 1959 

